The feet and the hands both include numerous bones and joints that cooperate together to define quintessential human movement. They are sophisticated, delicate and altogether elegant in function and design. Together the foot and ankle have over 25 bones and 33 joints along with more than 100 named muscles, tendons, and ligaments and a network of blood vessels, nerves, all residing beneath a relatively slim covering of soft tissue and skin. Structurally, the foot has three main anatomical regions: the forefoot, the midfoot, and the hindfoot. These parts work together with the ankle, to provide the body with support, balance, and mobility. A structural flaw or malfunction in any one part can result in the development of problems, which are manifested in other areas of the body. The hand forms a cognate to the foot with 27 bones within the hand and wrist. There are eight small bones within the wrist called the carpals, which join with the radius and the ulna to form the wrist joint. The carpals connect with the five metacarpals to form the palm of the hand, which terminate in the rays (i.e., the thumb and fingers) formed by the phalanges. The three phalanges in each finger are separated by two joints, called interphalangeal joints (IP joints). The one closest to the MCP joint (knuckle) is called the proximal IP joint (PIP joint). The joint near the end of the finger is called the distal IP joint (DIP joint). The thumb only has one IP joint between the two thumb phalanges. The IP joints of the digits also work like hinges when you bend and straighten your fingers and thumb.
Similarly, the forefoot includes the five toes (which are also known as the “phalanges”) and their connecting long bones (or “metatarsals”). Several small bones together comprise a phalanx or toe. Four of the five toes have three phalanx bones respectively connected by two joints. The big toe (or “hallux”) has two phalanx bones distal and proximal with a joint in between called the interphalangeal joint. The big toe articulates with the head of the first metatarsal at the first metatarsophalangeal joint (the “MTP” joint) and there are two tiny, round bones called sesamoids on the plantar side of the metatarsal head. The phalanges are connected to the metatarsals at the ball of the foot. The forefoot balances pressure on the ball of the foot and bears a substantial amount of the body weight. The first metatarsal forms a joint at the mid-foot with the cuneiform. This joint is referred to as the MTC joint or metatarsocuneiform joint. In the native position, the first metarsal is relatively parallel to the second metatarsal. When bunions are formed, the first metatarsal becomes displaced at an angle relative to the second metatarsal, and often in response, the big toe subluxates.
The bones of the midfoot from medial to lateral are the 1st through 3rd cuneiform, the cuboid, and the crescent shaped navicular bone posterior to the cuneiforms, which also forms a joint with the talus that forms the basis for the ankle joint at the hinged intersection of the tibia, the fibula, and the foot. The five tarsal bones of the midfoot act together form a lateral arch and a longitudinal arch, which help to absorb shock. The plantar fascia (arch ligament) underlays the bones of the midfoot and along with muscles, forms a connection between the forefoot and the hindfoot. The toes and their associated midfoot bones form the first through fifth rays beginning with the great toe as the first ray. The bones which form the palmate portion of the hand are: the scaphoid, the lunate, the triquetrum, the pisiform, the trapezium, the trapezoid, the capitate, and the hamate, which act in concert to allow the opposition of the thumb with each of the fingers and to permit the uniquely human ability to manipulate objects.
The hindfoot is composed of three joints (subtalar, calcaneocuboid & talonavicular) and links the midfoot to the ankle. The heel bone (or “calcaneus”) projects posteriorly to the talus and forms a lever arm to activate the hinged action of the foot so as to allow propulsion of the entire body from this joint. The calcaneus is joined to the talus at the subtalar joint. The mid-foot is often the subject of trauma, such as results from falls, vehicle crashes and dropped objects. These accidents often result in severe fractures and/or dislocations. In addition, there are several conditions which result from congenital deformation or which arise as a result of repeated use type injuries. Surgical intervention that includes surgical sectioning of bone or an “osteotomy” is often used to restructure the bones as a treatment for such conditions, for example, the bunionectomy. The present invention is likewise useful for conditions of the hand that result from prior trauma, surgical intervention or defects from birth or that develop with age (such as rheumatoid arthritis).
Examples of some of the other procedures with which the present invention could be used include hallus valgus and hallus rigidus corrections, as well as lapidus surgeries. Other applications, which could use the present invention, include first and fifth metatarsal chevrons, translational osteotomies, closing wedge osteotomies, pediatric femoral osteotomies, metacarpal and calcaneal rotational osteotomies, intrarticular osteotomies and hand and wrist realignment osteotomies. Specific surgical techniques are discussed for the use of an embodiment of the invention designed for use in bunionectomies specifically involving the MTP and MTC joints.
Typical surgical treatment of the foot or hand re-establishes a normal anatomy while the fractured bones mend. In some cases, fusion of a joint may be necessary, for example, where arthritis arises in a patient due to use injuries, poor bone or prior unsuccessful surgeries. One current surgical treatment of these conditions requires that pins, wires and/or screws be inserted to stabilize the bones and joints and hold them in place until healing is complete. For example, a pin or interfragmentary screw may be introduced medially into the internal cuneiform and through the base of the first and/or second metatarsal bone. While the use of k-wires, pins, and screws may provide acceptable results for younger and more plastic patients, these methods of fixation are not always satisfactory, in particular in cases of early weight-bearing on the operative joint, which can result in secondary issues such as elevated metatarsal, plastic deformation, or lesser metatarsal overload.
The present invention combines the advantages of the prior art screw/pin fusion methods with the advantages of a plate, and allows the surgeon the option of using an inter-fragmentary or fusion compression screw in a procedure that also incorporates a plate and thus provides the advantages for stress shielding and force loading or balancing that permits earlier weight bearing. Templates are provided which facilitate the operative procedure, including alignment holes for the positioning of guide wires which can remain in position during placement of the plate, counter-boring the surgical site to accommodate the compression screw housing and placement of the “inter-fragmentary” or compression screw. Further, the plate includes elongated wire and/or screw holes that allow for the compression and attendant relative bone movement during the surgery by the engagement of the compression screw. The compression screw or screws are placed in the plate so as to minimize the possibility of interference with the guide wires and plate screws. The openings in the plate for the compression screws are provided in a peripheral, and/or distal portion of the plate, and further for some applications are displaced from and do not lie on the long axis of the plate body, but are offset from by means of a longitudinal curve in a extended or tail portion of the plate which receives the screw or by providing a peripheral tab that curves inward so as to wrap the axis. This allows a placement of the compression screw that exerts a force on a diagonal to the long axis of the plate (i.e. a compound force relative to the plate). Further, in one embodiment, a compression housing or “pocket” is provided which projects below the bone-facing surface of the plate, which includes a slotted opening for the compression screw. Thus, the screw can be angled with a single degree of freedom (i.e. linearly) with respect to the axis of the compression screw hole in the housing.
Finally, in a plate system in accordance with the present invention, a surgical tray is provided with a series of plates that include a varying degree of offset to accommodate the correction for a varying degree of anatomical deformity in a lapidus procedure. Preferably this system provides for a left and right set of plates, each set optionally including a first plate that has a compression slot rather than a shrouded compression housing, a “neutral” plate having a compression housing and a 3.5° offset between the posterior and anterior end of the plate, a 4° plate that has a total offset of 7.5°, a 8° plate that has a total offset of 11.5° (all angles being expressed at +/−0.5°) and a medial column plate that is designed to provide for additional fixation of the first ray. At a minimum, the sets include the first plate which is considered “neutral” (and has an offset of 2.5°-4.5°), the second plate which has an additional offset of 2° to 5° (for a total of 4.5°-9.5°) and a third plate has an additional offset of 6° to 10° (for a total of 10° to 20°). The system provides for at least these three plates available during a surgery in a single tray, and additionally the system provides for a left set and a right set of implants, for a total of at least six plates available to the operating surgeon. Optionally, the system may also include a non-pocket plate that has a double tabbed end and an opposing tri-lobed end with the intermediate lobe including a compression slot, and the system may include a medial column plate that has a series of threaded medial tabs for locking screws and at one end a lobe that has a terminal compression slots to achieve compression toward the other end of the plate, and the other end of the plate has a middle compression slot which acts to achieve compression towards the middle of the plate.